p16 Immunostaining Allows for Accurate Subclassification of Vulvar Squamous Cell Carcinoma Into HPV-Associated and HPV-Independent Cases

Clinical and molecular classification of vulvar squamous pre-cancers

Vulvar intraepithelial neoplasia (VIN) is a precursor to vulvar squamous cell carcinoma and is defined histopathologically by the presence of atypia. VIN has been classified into two types: usual vulvar intraepithelial neoplasia (uVIN), which is also referred to as a vulvar high-grade squamous intra-epithelial lesion (HSIL), and differentiated VIN (dVIN). The former is associated with chronic infection by sub-types of the human papilloma virus (HPV), whereas dVIN is HPV-independent and frequently associated with lichen sclerosus. The distinction is important because dVIN has a greater risk of, and more rapid transit to, vulvar squamous cell carcinoma. Furthermore, dVIN-associated vulvar cancers have an increased risk of recurrence and higher mortality than those arising from HSIL. Molecular characterization of vulvar squamous cell carcinoma precursors using next-generation sequencing is a relatively novel, but rapidly advancing field. This review appraises recent studies that have investigated the risks of progression to vulvar malignancy associated with HSIL and dVIN, the prognosis of HPV-dependent and HPV-independent vulvar squamous cell carcinomas, and conducted next generation sequencing mutation analyses to elucidate the genomic profiles underlying VIN. These studies suggest that HSIL and dVIN are characterized by different underlying molecular alterations that may have important implications for treatment and follow-up of women diagnosed with vulvar squamous cell cancer.

Tumor cell-specific Serpin A1 expression in vulvar squamous cell carcinoma

Purpose

The two main etiological factors for vulvar squamous cell carcinoma (vSCC) are the vulvar dermatosis lichen sclerosus (LS) and high-risk human papillomavirus (hrHPV). Serpin A1 (α1-antitrypsin) is a serine protease inhibitor, which plays a role in the tumorigenesis of various cancer types. The aim of the study was to evaluate the expressions of Serpin A1 in LS, premalignant vulvar lesions, and vSCC using immunohistochemistry (IHC) and serum analysis, and to compare Serpin A1 stainings to the tumor markers p53 and p16.

Methods

In total, 120 samples from 74 patients were studied with IHC for Serpin A1, p53 and p16: 18 normal vulvar skin, 53 LS, 9 premalignant vulvar lesions (dVIN/HSIL) and 40 vSCC samples. Serum concentrations of Serpin A1 were analyzed from 30 LS, 44 vSCC and 10 control patients. Expressions were compared to clinical data.

Results

Tumor cell-specific Serpin A1 overexpression was detected in 88% of vSCC samples, independent of the etiology. The intensity of Serpin A1 expression was significantly higher in vSCC than in healthy vulvar skin, LS, or premalignant vulvar lesions. Serpin A1 showed an association with p53 positivity. No difference in overall survival was found between Serpin A1-, p53-, or p16-positive vSCC patients. Serum concentrations of Serpin A1 were equal in the LS, vSCC, and control groups.

Conclusion

Tumor cell-specific Serpin A1 overexpression is a potential biomarker in vSCC.

HPV-independent Differentiated Vulvar Intraepithelial Neoplasia (dVIN) is Associated With an Aggressive Clinical Course

Differentiated vulvar intrapeithelial neoplasia (dVIN) is an human papillomavirus (HPV)-independent precursor of squamous cell carcinoma (SCC), and the aim of this study was to better characterize its natural history. Cases of dVIN were identified from the pathology archives. Outcomes of patients with dVIN only, without associated invasive SCC, were compared with a cohort of patients with high-grade squamous intraepithelial lesion [HSIL(VIN3)]. Eighteen patients diagnosed with dVIN with adjacent invasive SCC (SCC/dVIN) and 7 patients with dVIN only, without invasive carcinoma, were identified. Mean age in both cohorts was 75 yr. All lesions but 1 were unifocal. In 35% of SCC/dVIN cases the surgical resection margins were positive for SCC, with 75% and 60% having margins positive for dVIN in the SCC/dVIN and dVIN-only cohorts, respectively. In total, 23/25 women with dVIN only or dVIN/SCC, for whom there was follow-up information, experienced either progression to or recurrence of invasive SCC, respectively, at a median of 1.1 yr, including all but 1 case of dVIN only, where the median time of progression to invasive SCC was 1.9 yr. A total of 22/25 women died of disease with a median overall survival of 3.4 yr. The outcome (i.e. progression to invasive carcinoma) of patients with dVIN only was significantly worse than that of a comparison group of 18 patients with HSIL(VIN3) (progression-free survival log-rank, P<0.001; disease-specific survival, P=0.04; overall survival, P=0.01). Six of 7 patients with dVIN only developed invasive carcinoma on follow-up, compared with 0 of 18 patients with HSIL(VIN3). The diagnosis of dVIN indicates the presence of a high-risk human papillomavirus-negative precursor of invasive SCC. These patients are likely to progress to invasive carcinoma over a relatively short period, at which point their prognosis is guarded.

Does Differentiated Squamous Intraepithelial Neoplasia Occur in the Cervix?

BACKGROUND

Invasive cervical cell squamous carcinoma (ICC) classically develops from high grade cervical intraepithelial neoplasia of usual type (uCIN). Differentiated cervical intraepithelial neoplasia (dCIN) analogue to differentiated vulvar intraepithelial neoplasia has not been described in the cervix.

METHODS

A pilot case of ICC developing from dCIN with atypia limited to the basal/parabasal layers, focally associated with neoplastic spread above the parabasal layer (usual-like CIN pattern or u-like CIN) was identified. The previous cervical biopsy was under-diagnosed as low grade CIN. A total of 33 consecutive cases of ICC were reviewed to identify dCIN, u-like CIN and uCIN.

RESULTS

The ICC developed from dCIN/u-like CIN in 2 patients, 46 and 47-year-old (group 1), mixed dCIN/u-like CIN and uCIN in 7 patients, 36±3-year-old (group 2) and from uCIN in 24 patients, 47±9-year-old (group 3). In group 1, focal uCIN but not connected to ICC was also seen and Pap smears showed only hyper-keratinized cells with mildly atypical nuclei. Endocervical gland involvement by CIN was absent in group 1, focal in group 2 and extensive in group 3. All cases showed diffuse p16 staining. P53 reactivity was noted in basal/parabasal in dCIN, predominantly lower and upper parts of the epithelium in groups 2 and 3, respectively.

CONCLUSIONS

Totally, 27% of ICC cases had associated dCIN/u-like CIN and in younger patients than in the uCIN group. Larger studies are needed to confirm dCIN/u-like CIN as significant precursor lesions of ICC.

Role of Human Papillomavirus in Vulvar Cancer

Human papillomavirus (HPV) is involved in one of the at least 2 pathways leading to vulvar squamous cell carcinoma (VSCC). Inactivation of p53 and retinoblastoma by the viral products E6 and E7 is involved in malignant transformation. The percentage of HPV-positive VSCCs ranges from 18% to 75%, depending on the geographical area. HPV-associated tumors affect relatively young women and arise from high-grade intraepithelial lesions, identical to other HPV-associated premalignant lesions of the anogenital tract. HPV-independent tumors tend to affect older women and usually arise in a background of inflammatory skin disorders and a subtle variant of in situ lesion called differentiated vulvar intraepithelial neoplasia. HPV-positive tumors tend to be of basaloid or warty types, whereas HPV-independent tumors tend to be of keratinizing type, but there is frequent overlap between histologic types. There is no conclusive evidence yet on the best strategy in terms of determining HPV attribution. HPV DNA detection is generally considered the gold standard although there is some concern about misclassification when using this technique alone. p16 immunostaining has shown to be an excellent surrogate marker of HPV infection. Positive results for both techniques are considered the best evidence for HPV-association. The prognostic role of HPV in VSCC is still contradictory, but increasing evidence suggests that HPV-associated tumors are less aggressive. Currently, there are no differences in treatment between HPV-associated and HPV-independent VSCC, but novel immunological strategies based on anti-HPV antigens are being evaluated in clinical trials.

Human papillomavirus (HPV)-independent vulvar squamous cell carcinoma has a worse prognosis than HPV-associated disease: a retrospective cohort study

AIMS

Vulvar squamous cell carcinoma (VSCC) can be subdivided by human papillomavirus (HPV) status into two clinicopathological entities. Studies on the prognostic significance of HPV in VSCC are discordant.

METHODS AND RESULTS

We performed a retrospective analysis of overall survival (OS), disease-specific survival (DSS) and progression-free survival (PFS) in 217 patients with VSCC. Cases were extracted from an era of more aggressive en-bloc radical dissections (1985-95) and more localized radical surgery through separate vulvar and groin excisions (1996-2005). p16 immunohistochemistry was used as a surrogate for HPV status. HPV status could be determined in 197 tumours, 118 HPV-independent and 79 HPV-associated tumours. Patients with HPV-associated tumours were younger (mean 58.8 versus 71.6 years for HPV-independent tumours, P < 0.0001) and more likely to have prior abnormal cervical cytology (41.1 versus 5.6% for HPV-independent tumours, P < 0.0001). In univariable analysis, patients with HPV-associated tumours had superior PFS [hazard ratio (HR): 0.37, 95% confidence interval (CI): 0.18-0.70], DSS (HR: 0.19, 95% CI: 0.08-0.41) and OS (HR: 0.35, 95% CI: 0.21-0.59). This was driven by worse outcomes (PFS, DSS and OS) for patients with HPV-independent tumours compared with HPV-associated tumours who underwent surgery after 1995. After adjusting for age and stage in multivariable analysis, patients with HPV-associated tumours showed superior PFS (HR: 0.25, 95% CI: 0.07-0.77) and DSS (HR: 0.21, 95% CI: 0.04-0.78).

CONCLUSIONS

VSCC can be stratified into two prognostically different diseases based on p16 immunostaining. HPV status was associated only with prognosis in the cohort that underwent surgery after 1995, suggesting that more conservative surgery may have led to worse outcomes for patients with HPV-independent tumours.

The changing landscape of gynaecological cancer diagnosis: implications for histopathological practice in the 21st century

The era of molecular medicine has led to dramatically improved understanding of the genetic events that give rise to different types of cancers. In the case of gynaecological malignancies, this has resulted in distinct shifts in how these tumours are diagnosed in routine surgical pathology practice, with an increased emphasis on accurate subtype diagnosis. This has happened across all sites in the gynaecological tract and for most cell types, but in ways that are site-specific and may appear to be subtle, as in most instances the diagnostic terminology has not changed. For example, the diagnosis of clear cell carcinoma of the ovary is still in use, but the diagnostic criteria and clinical implications are different in 2017 from what they were in 2000. As a result, there can be a failure to appreciate how important these changes are and the resulting necessity of incorporating them into our daily practice. In this review we will describe changes in diagnostic surgical pathology occasioned by improved understanding of molecular events during pathogenesis, for cancers of ovary/tube, endometrium, cervix and vulva, and highlight how current practice differs from that of only a few years ago.

Squamous precursor lesions of the vulva: current classification and diagnostic challenges

Growing evidence has established two major types of vulvar intraepithelial neoplasia (VIN), which correspond to two distinct oncogenic pathways to vulvar squamous cell carcinoma (VSCC). While the incidence of VSCC has remained relatively stable over the last three decades, the incidence of VIN has increased. VIN of usual type (uVIN) is human papillomavirus (HPV)-driven, affects younger women and is a multicentric disease. In contrast, VIN of differentiated type (dVIN) occurs in post-menopausal women and develops independent of HPV infection. dVIN often arises in a background of lichen sclerosus and chronic inflammatory dermatoses. Although isolated dVIN is significantly less common than uVIN, dVIN bears a greater risk for malignant transformation to VSCC and progresses over a shorter time interval. On histological examination, uVIN displays conspicuous architectural and cytological abnormalities, while the morphological features that characterise dVIN are much more subtle and raise a wide differential diagnosis. On the molecular level, dVIN is characterised by a higher number of somatic mutations, particularly in TP53. Here we review the classification, epidemiology, clinical features, histomorphology, ancillary markers and molecular genetics of both types of VIN, and discuss the morphological challenges faced by pathologists in interpreting these lesions.